So a little background: I am trying to construct a superhet radio with an oscillator producing a harmonic-rich output that can be electrically coupled to a mixer, the idea being one of the harmonics can heterodyne with the RF signal. After doing research regarding the construction of Armstrong-type tube oscillators I have found that the majority of designs (or at least those using a tuning capacitor where one side is earthed) follow one of the three topographies shown in the attached picture. I am wondering what the advantages/disadvantages to each design are. My source calls A the Meissner variant and states it's practical purposes are limited, B seems to be the most commonly used variant, and C appears to be used in the mixers of older superheterodyne radios (suggesting maybe it's more resistant to an electrically-coupled load?). Thanks in advance.